• Methods

• The Scientific Method
• ##### Did you know?

Did you know that there are many ways to go about finding the answer to a scientific question? Scientific discovery can be sparked by various inspirations and carried out using different methods in steps that may not follow a tidy path with predictable results. Scientists may use one, several, or a combination of methods to investigate phenomena.

##### Summary

Scientific investigation is not always a linear process that starts with a hypothesis and ends with a conclusion, as portrayed in the classic “Scientific Method.” The true scientific method is a much more dynamic and much less predictable, and can involve various methods that may overlap. This module serves as an introduction to our Practice of Science series of modules, which describe key scientific methodologies.

##### Key Concepts
• The scientific method is a process of discovery that does not follow a prescribed, linear pattern of steps.

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• Measurement

• The Metric System
• ##### Did you know?

Did you know that the metric system of measurement is used in almost every country in the world? The beauty of the metric system is that one unit of measurement is used for each type of thing measured, so volume is always measured in liters whether talking about how much water is in a single raindrop or in one of the Great Lakes.

##### Summary

The metric system is the standard system of measurement in science. This module describes the history and basic operation of the metric system, as well as scientific notation. The module explains how the simplicity of the metric system stems from having only one base unit for each type of quantity measured (length, volume, and mass) along with a range of prefixes that indicate multiples of ten.

##### Key Concepts
• The metric system, also known as the Système international d'unités (SI), was developed in the late 1700s to standardize units of measurement in Europe.
• The metric system is the primary system of measurement used through much of the world and in science.
• Each type of measurement has a base unit to which prefixes are added to indicate multiples of ten.
• Scientific notation is a shorthand for writing very small and very large numbers.

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• Physical Properties

• Temperature
• ##### Did you know?

Did you know that in theory there can be no temperature in the universe lower than zero on the Kelvin scale, known as “absolute zero”? This is the point where every molecule stops moving. Although there are different temperature scales – Fahrenheit, Celsius, and Kelvin – they all do one thing: put a number to the heat energy possessed by an object.

##### Summary

This module provides an introduction to the relationship between energy, heat, and temperature. The principle behind thermometers is explained, beginning with Galileo’s thermoscope in 1597. The module compares the three major temperature scales: Fahrenheit, Celsius, and Kelvin. It discusses how the different systems use different references to quantify heat energy.

• ##### NGSS
• HS-C3.5, HS-C5.3, HS-PS3.A2
##### Key Concepts
• There are three different systems for measuring heat energy (temperature): Fahrenheit, Celsius, and Kelvin.
• In scientific measures, it is most common to use either the Kelvin or Celsius scale as a unit of temperature measurement.
• Nothing can be colder than absolute zero, which is the point at which all molecular motion ceases.

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• Density
• ##### Did you know?

Did you know that submarines submerge and resurface by changing their density? Density explains why large metal ships can float and why oil and vinegar separate into layers. Density has also been used to solve crimes: around 250 BCE Archimedes used the concept to reveal that a craftsman defrauded the king by replacing gold in his crown with silver.

##### Summary

Density is a fundamental physical property of matter. This module introduces the concept of density, explains how density is calculated, and lists the densities of common substances. The relationship between density and buoyancy is discussed. The module relates the concept of density to the operation of large ships, submarines, and hot air balloons.

• ##### NGSS
• HS-C3.5, HS-PS1.A3
##### Key Concepts
• Density is a physical property of matter that expresses a relationship of mass to volume.
• When materials of different densities are put in contact with one another, their densities will determine how they order themselves.
• An object's buoyancy is determined by its density in relation to the density of the surrounding liquid.

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